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$2.99 Flat Rate Shipping For Orders Under $29
Most orders under $29 ship for only $2.99 using a mix of economy shipping methods including UPS Ground, USPS First Class, and/or SurePost. Your order will be delivered in up to 7 business days after it ships out. Orders placed before 10:30 am PST Monday-Friday are shipped the same day. Our $2.99 flat rate shipping is only available within the contiguous United States. Frozen foods, live foods, and items shipped directly from the manufacturer do not qualify for $2.99 flat rate shipping.
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Reef Kalkwasser™ is a pure calcium hydroxide with unsurpassed purity and solubility characteristics. Calcium hydroxide is used to prepare limewater (kalkwasser) solutions that will maintain calcium concentrations at natural seawater levels. Kalkwasser solutions maintain calcium directly and carbonate alkalinity indirectly. However, its capacity to perform these functions is dependent on evaporation rate and CO2 concentration. If these two factors are insufficient you can provide additional calcium with Reef Advantage Calcium™, Reef Complete™, or Reef Calcium™, and carbonate alkalinity with Reef Builder™ or Reef Carbonate™ (do not mix these directly with a kalkwasser solution).
While Reef Kalkwasser™ is a high purity and economical limewater mix, the beginner, or someone with not as much time to devote to their system, may prefer to use other less involved methods for maintaining proper ionic concentration levels.
Directions for use: Never add this product directly to the tank. Add 3 g (1 teaspoon) to 4 L (1 US gallon) of water and mix to dissolve. If using pure water, a fully saturated solution is prepared by adding 6 g (2 teaspoons) to 4 L (1 US gallon). Drip this solution into tank. Monitor pH and carbonate alkalinity. Adjust rate of addition to maintain a stable pH (8.3–8.4). Notes: Adding 4 L (1 US gallon) of a saturated kalkwasser solution to 150 L (40 US gallons) will raise calcium by 24 mg/L. Always use the clear supernatant (top solution) only and do not allow undissolved material to enter the aquarium. Keep this container tightly closed when not in use and minimize solution/air contact to avoid calcium carbonate formation/precipitation.
Manufacturer Info
Seachem Seachem Laboratories, Inc. was established in 1980 by Dr. Leo G. Morin. Seachem moved into a state of the art 110,000 square foot facility in Madison, Georgia marking their 25th anniversary in the industry in 2005. This facility includes production and research laboratories, manufacturing, inventory, shipping, and office space.
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This was my first time using Kalk and I wont go back. I like low tech when possible so I mix this up in two quart batches which last me four days in a gravity drip. My corals look great! My pH is great. My chemistry is great. Sooooo easy and fool proof.
The first thing we noticed was it seems to dissolve much easier than other brands we have tried and most of all it totally leveled out out parameters then we backed way off on useing other dosing materials clearly the corals are showing signs of growth where we were kind of stagnant growth period ve...Read More
The first thing we noticed was it seems to dissolve much easier than other brands we have tried and most of all it totally leveled out out parameters then we backed way off on useing other dosing materials clearly the corals are showing signs of growth where we were kind of stagnant growth period very easy to use we put it in with our ato and let it do its thingHide
Easy to use and able to buy in large sizes. I use in all my makeup water. My system holds about 300 gallons and evaporates 3-5 gallons a day depending on humidity. I have a calcium reactor that needs set up but I will still add a small amount of kalk to makeup water. I believe in using Seachem produ...Read More
Easy to use and able to buy in large sizes. I use in all my makeup water. My system holds about 300 gallons and evaporates 3-5 gallons a day depending on humidity. I have a calcium reactor that needs set up but I will still add a small amount of kalk to makeup water. I believe in using Seachem products, have been using them for over 20 years.Hide
I use 1/2cup of this product a week in my kalkwasser reactor (a must if you're serious about the health of a reef tank) and my pH & calcium levels are as steady as one could hope for. This is very simple to use if you have a kalkwasser reactor, but I wouldn't suggest this product to a beginner a...Read More
I use 1/2cup of this product a week in my kalkwasser reactor (a must if you're serious about the health of a reef tank) and my pH & calcium levels are as steady as one could hope for. This is very simple to use if you have a kalkwasser reactor, but I wouldn't suggest this product to a beginner as overdosing could harm the health of one's system. I am giving it 4 stars because I haven't used the whole bottle yet, and am waiting for completion of product before I praise it further.Hide
Most orders under $29 ship for only $2.99 using a mix of economy shipping methods including UPS Ground, USPS First Class, and/or SurePost. Your order will be delivered in up to 7 business days after it ships out.
free shipping for orders $29+
We ship 99% of the products we carry for free within the contiguous United States using a mix of economy methods including USPS First Class Mail, SurePost and UPS Ground. Your order will arrive in up to 7 business days. Just spend $29 or more!
free faster shipping for orders $250+
Over 90% of shoppers receive their orders within 1-2 business days. Upgrade from free economy shipping to faster shipping for only $2.99—or spend $250 and we'll upgrade you automatically!
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Same-day shipping is available Monday-Friday for most products—place your order by 10:30 am PST. Pre-ordered and back-ordered items do not qualify, nor do drop-shipped, live, or frozen shipments.
live plants, live foods, and frozen foods delivered to your door
We ship live plants, live foods, and frozen foods within the contiguous United States. Each of these categories is subject to its own $19.99 flat-rate shipping fee to cover the special packaging and/or expedited shipping costs required to ensure safe delivery. Orders with 12+ live plants ship free!
Return any new and unused item within 60 days for a full refund. Having difficulty with a product? Contact us to speak with an aquarium expert. If you need a replacement, fill out this form.
A small segment of the 180+ brands we carry require that customers contact them directly if/when problems arise. You can view the full list of those brands and get their contact info here.
We are unable to accept returns of Digital Aquatics, Neptune Systems, Vertex Aquaristik, Aqua Illumination (AI), EcoTech Marine, GHL, or Seneye products once the manufacturer's packaging seals have been broken.
Marine Depot is an authorized reseller for every product we carry. That means when you buy aquarium supplies from us, your products are not only backed by our own 60-day return policy, they also carry full factory warranties, where applicable. Some items have a 1-year warranty, others have limited lifetime warranties. Warranty coverage varies from manufacturer to manufacturer, so please read the product description of the item(s) you are considering thoroughly for details or contact us if you have warranty questions.
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